39 research outputs found

    Blends of synthetic plastic-derived polypeptide with Hydroxypropylmethylcellulose and polyvinyl alcohol: unraveling the specific interaction parameters, morphology and thermal stability of the polymers couple

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    The medleys of the plastic-derived polypeptide with commercially available polymers believably the suitable candidate for pharmaceutical and biomedical importance. The current research is focussed on the synthesis of a novel plastic-mimetic polypeptide (PLP), poly(IPAVG) by the solution phase method (where I, P, A, V, and G represent Isoleucine, Proline, Alanine, Valine, and Glycine, respectively). The miscibility attributes of PLP/polyvinyl alcohol (PVA) and PLP/hydroxypropylmethylcellulose (HPMC) blends were examined by viscometry and by other advanced analytical tools for different weight proportions. It is shown by the viscometry that the PLP/HPMC and PLP/PVA form an immiscible blend system at 10(omicron)C and further, the FTIR spectra of poly (IPAVG) /HPMC and poly (IPAVG) /PVA blend membranes manifest the lack of intermolecular interactions. DSC results proved the dual Tg for one blend proportion and lower Tg values for all other blend systems. The thermal property of the blends with different compositions was evaluated by thermogravimetric analysis (TGA). The TGA results showed that the blends possess inferior thermal stability to the native ones. The surface morphology was analyzed by SEM indicated the heterogeneity and X-ray diffraction (XRD) revealed the absence of any change in crystallinity advocated the immiscibility of the blends. Further, we ventured to prepare the non-woven fabrics from the solutions of 1-10 wt% concentrations at the voltages within 20-30 kV by electrospinning. The droplet formed at the spinneret failed to reach the collector plate, and consequently, no films developed for the collector device

    Increased cerebral blood flow in the right frontal lobe area during sleep precedes self-awakening in humans

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    <p>Abstract</p> <p>Background</p> <p>Some people can subconsciously wake up naturally (self-awakening) at a desired/planned time without external time stimuli. However, the underlying mechanism regulating this ability remains to be elucidated. This study sought to examine the relationship between hemodynamic changes in oxyhemoglobin (oxy-Hb) level in the prefrontal cortex and sleep structures during sleep in subjects instructed to self-awaken.</p> <p>Results</p> <p>Fifteen healthy right-handed male volunteers with regular sleep habits participated in a consecutive two-night crossover study. The subjects were instructed to wake up at a specified time (“request” condition) or instructed to sleep until the morning but forced to wake up at 03:00 without prior notice (“surprise” condition). Those who awoke within ± 30 min of the planned waking time were defined as those who succeeded in self-awakening (“success” group). Seven subjects succeeded in self-awakening and eight failed.</p> <p>No significant differences were observed in the amounts of sleep in each stage between conditions or between groups. On the “request” night, an increase in oxy-Hb level in the right prefrontal cortex and a decrease in δ power were observed in the “success” group around 30 min before self-awakening, whereas no such changes were observed in the “failure” group. On the “surprise” night, no significant changes were observed in oxy-Hb level or δ power in either group.</p> <p>Conclusions</p> <p>These findings demonstrate a correlation between self-awakening and a pre-awakening increase in hemodynamic activation in the right prefrontal cortex, suggesting the structure’s contribution to time estimation ability.</p
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